A conventional dryer in a paper mill comprises two rows of heated drying cylinders about which the wet web is trained forming a series of adjacent pockets. To optimize the heat transfer from the dryer cylinders to the web, the so-called "dryer fabrics" are provided which press the web in intimate contact with the dryer cylinders. Typically, one dryer fabric is provided for each row of drying cylinders, passing from one cylinder to another of the row through a guide roller. This arrangement is such that the web runs exposed in its travel from a tangency with the cylinder of one row to a tangency with a cylinder of the other row. While in contact with a drying cylinder, the web is pressed against that cylinder by a dryer fabric.
In order to evacuate the moisture ladden air which accumulates in the adjacent pockets during the operation of the dryer, it is known to utilize a ventilation system which injects a dehydrating gas in each pocket, such as hot air, evacuated through the open ends of the pocket. This system has been proven unsatisfactory because the amount of injected air in the pocket over pressurizes the pocket. This air must be evacuated through the open end of the pocket; the air exiting the pocket generates turbulence and causes web flutter. Web flutter then causes web break and costly loss of production.